1. Field of the Invention
The present invention relates to an image forming apparatus, and in particular, to a consumable item supplying system capable of supplying a consumable item from a consumable item supplying center under control of a central controlling apparatus connected with a plurality of image forming apparatuses when some consumable items are requested by the image forming apparatuses.
2. Discussion of the Background
In recent years, a variety of consumable item supplying systems have been proposed which include at least a central control apparatus for receiving a request for a consumable item from one of image forming apparatuses. The central control apparatus can order delivery of consumable items from a consumable item supplying center to the image forming apparatuses.
When the image forming apparatuses are copiers, such a consumable item supplying system generally has a function of sending a message including data indicating numbers of copysheets used or an amount of toner used, for example, from the copiers to the central control apparatus. Based on such a sent message, the consumable items, for example a copysheet or toner, to be used in the copiers are supplied at a predetermined timing from the consumable supplying center under control of the central control apparatus.
As illustrated in Japanese Laid Open patent Application Nos. 08-152814 and 08-152824, an amount of a consumable item remaining in an image forming apparatus is always monitored by a controller to avoid a shortage thereof, and such that a consumable item can be automatically supplied to the image forming apparatus when the consumable item remaining therein decreases to a predetermined number or amount.
However, in such background consumable item supplying systems, a copysheet having a toner image formed on one side thereof is sometimes reused to form a copy on the other side thereof, to thereby save natural resources. This results in that a total copy count counted by a copy counter of the image forming apparatus does not correspond to the amount of copy streets actually remaining in the copier. Accordingly, a request for supplying new copy sheets which is automatically made when copysheets remaining therein reach a predetermined amount is not precise in such background systems.
Further, if a large number of copysheets are to be copied at one copying operation, an amount of a predetermined sized copysheet may decrease to less than a predetermined amount during such a copying operation. However, a request for supplying new copysheets of the predetermined size is made only when the copysheets remaining therein reach the predetermined amount. This means that a request is not made before the copying operation of such a large number of copies is started. Therefore, the delivery of the new consumable item requested may be delayed, and an operator may have to stop the copying operation using such a consumable item until the requested consumable item is ordered and delivered.